JPH02301161A - Transfer-molded hybrid integrated circuit - Google Patents

Abstract

PURPOSE:To improve the property of solder creeping up to the cross section part of a lead tip and heighten the reliability and quality of soldering, by providing a metal plating finished surface in addition to a surface where lead frame raw material is exposed, at the cross section part of the outer lead tip of a lead frame. CONSTITUTION:The part of the cross section of the outer lead tip 3 of a lead frame 6 has not only a cut cross section by the work of the lead cutting but also parts which are not influenced by the work, namely, gap surfaces in the lead made by narrowing the lead width from the spot of the outer lead tip 3 to be worked by cutting to the outside frame of the lead frame to the extent of 1/4-1/3 of the lead width used as a product by etching system or press working, before the lead frame being assembled. Then, the gap surfaces are metal- plated beforehand, and these surfaces become parts of the cross section of the outer lead tip as they are.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a transfer mold type hybrid integrated circuit, and particularly to a lead cross-sectional structure at the tip of an outer lead portion.

[Conventional technology]

A conventional hybrid integrated circuit of this type is shown in FIG. 4(a).

As shown in (b), the lead frame material remained exposed due to the cutting that occurred during the lead cutting process for the entire cross section of the tip of the outer lead portion.

[Problem to be solved by the invention]

The cross section of the tip of the outer lead of the conventional hybrid integrated circuit described above is a cut surface created during lead cutting, that is, the lead frame material remains exposed.

Therefore, the cut surface is rough and the surface is easily oxidized, so when the outer leads are connected by soldering, the solder does not rise to the cross section of the lead tips.

[Means to solve the problem]

The present invention relates to a transfer mold type hybrid integrated circuit in which a circuit board is bonded to a metal island and a lead frame on which semiconductor components and the like are mounted is sealed with a resin. In the cross section of the tip of the lead part, there is a part that is not affected by the cutting process other than the cut surface during the lead cutting process, that is, a part that is not affected by the cutting process when the lead frame is used alone, from the part where the outer lead tip is cut to the outer frame of the lead frame. Regarding the leads, the width of the leads can be reduced to 100 μm by etching or press processing (1/4 of the lead width used as a product).
A gap surface is formed between the lead width and the width of the lead used as a product, and this gap surface is pre-plated with metal, and this surface is used as the cross section of the tip of the outer lead portion.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

1(a) and 1(b) show a first embodiment of the present invention. FIG. 1(a) is a longitudinal cross-sectional view of the lead cut after resin sealing; b) is an enlarged perspective view of the outer lead portion of FIG. 1(a).

FIG. 2 is a plan view of a single lead frame.

1 is an IC package, 2 is an outer lead, and 3 is its tip. A lead frame 6 is used in which the lead width between the outer frame of the core is narrower than the lead cutting point 7, and after mounting semiconductor components etc., resin sealing is performed. After solder plating, the lead is cut from a lead cutting point 7 to form an outer lead tip having a cross section 5 and a metal-plated surface 4 in advance.

FIG. 3 is an enlarged perspective view of the tip of an outer lead showing a second embodiment of the present invention.

In this embodiment, the part where the material is exposed when the lead is cut is the lead side end, which has the advantage of increasing lead processing accuracy and reducing the area where the material is exposed.

〔Effect of the invention〕

As explained above, in the present invention, when the cross section of the outer lead tip is entirely exposed as the lead frame material, approximately 2/3 or more of the area is equivalent to the plated surface of the outer lead surface. By facing the
The solder build-up on the cross section of the lead tip is improved, the reliability of the solder connection is improved, and the number of man-hours for re-soldering can be significantly reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1(a) is a longitudinal sectional view showing a first embodiment of the present invention;
FIG. 1(b) is an enlarged perspective view of the outer lead portion of FIG. 1(a), FIG. 2 is a plan view of a single lead frame of the present invention, and FIG. 3 is an enlarged perspective view of the outer lead portion showing the second embodiment. 4(a) is an enlarged perspective view of an outer lead portion of a conventional example, and FIG. 4(b) is a plan view of a single lead frame of a conventional example.

1...IC package, 2...outer lead, 3
...Outer lead tip, 4...Metal plating finished surface, 5...Cross section during lead cutting process, 6...Lead frame, 7...Lead cutting location.

Claims (1)

[Claims] In a transfer mold type hybrid integrated circuit in which a metallic island circuit board is bonded and a lead frame on which semiconductor components, etc. are mounted is sealed with resin, the cross section of the tip of the outer lead part of the lead frame has a lead frame material. A transfer mold type hybrid integrated circuit characterized by having a metal-plated surface in addition to the exposed surface.